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On a chilly November Saturday after Thanksgiving, a team of
scientists departed Honolulu for a remote portion of the central
Pacific Ocean on the research vessel R/V Marcus G. Langsethin
search of clues that would help explain the rumbling of the
Earth.

Their mission was to address very basic questions about the
formation and evolution of oceanic tectonic plates, the jigsaw
puzzle-like sections of the Earth's crust that move across the
planet's surface and
bump against each other, creating earthquakes, volcanic
eruptions and new crustal rock.

The exact target of the mission was aswath of seafloor
approximately 1,200 miles (1,900 kilometers) southeast of Hawaii
where the ocean has anaverage depth of 16,700 feet(5,100 meters).
According to one of the mission scientists, Jim Gaherty, this
area was chosen because it contains some of the oldest
oceanic crust on the planet and it has not been modified by
other volcanic activity since it was formed 70 million years
ago.

"We hope that the structure of this mature, pristine oceanic
plate can illuminate the most basic aspects of plate formation
and evolution," said Gaherty,a research scientist at the
Lamont-Doherty Earth Observatory, who also
blogged about the experience.

Sea sickness

The team of 13 scientists and 34 crew members faced some
challenges on their initial voyage. Research ships travel at 10
knots (a whopping 12 mph) and the first few days were filled with
sickness as the researchers adjusted to large rolling waves and
strong winds.

Four days after departing Honolulu, they began deploying
ocean-bottom seismometers and seafloor magneto-telluric
instruments over a grid spanning 360 by 250 miles (580 by 400
km). The instruments measure natural electrical fields and
magnetic fields simultaneously.

"These fields can be used to infer the conductivity structure of
the rocks at depth. The combination of seismic velocity and
electrical conductivity are very useful for determining the
composition, temperature and melt content of the rocks that make
up the plate; these, in turn, allow us to better understand the
evolution of the plate," Gaherty told OurAmazingPlanet.

Tight schedule

Living and doing science aboard the research vessel requires a
very tight schedule and a round-the-clock attitude. "The ship is
expensive to operate, so we don't want to waste any time,"
Gaherty said.

The team splits up into 12-hour shifts to make sure the
instruments are deployed and data are collected properly. "Some
days are extremely busy —we deployed 17 seismometers in one
12-hour shift," he said. Other days are spent finishing work that
has been neglected from their jobs back on land.

The month-long voyage was just the beginning of the project to
delve deep into the ocean's plates. Gaherty predicts the team
will spend the better part of the next year carefully analyzing
this data, producing images of the subsurface and then
integrating the data from ocean-bottom seismometers.

"Based on those results, we will then think about what we have
learned about
plate evolution, what more questions still need to be
answered, and how and where we need to go to answer those
questions,"Gaherty said.